1. Field of the Invention
The present embodiments relate to a dye (photosensitizer) for a dye-sensitized solar cell and a dye-sensitized solar cell prepared from the same. More particularly, the present embodiments relate to a dye for a dye-sensitized solar cell that is capable of improving photovoltaic efficiency, an open-circuit voltage of a solar cell, and a dye-sensitized solar cell with improved photoelectric efficiency.
2. Description of the Related Art
Diverse research has been carried out in an attempt to develop energy sources that can replace conventional fossil fuels and solve the approaching energy crisis. Particularly, extensive research is underway to find alternative energy sources, such as wind power, atomic power, and solar power, as substitutes for petroleum resources, which are expected to be depleted within several decades. Among the alternative energy sources, solar cells use solar energy that is essentially infinite and environmentally friendly, as opposed to other energy sources. Since 1983 when a Se solar cell was first produced, solar cells have been highlighted, and Si solar cells have recently been drawing attention from researchers.
However, it is difficult to practically use Si solar cells because the production cost is high and there are difficulties in improving cell efficiency. To overcome the problem, researchers are studying development of a dye sensitized solar cell that can be produced at a low cost.
Different from the Si solar cell, the dye sensitized solar cell is an electrochemical solar cell that is mainly composed of photosensitive dye molecules that absorb visible rays and produce electron-hole pairs, and a transition metal oxide that transfers the produced electrons. Among conventional dye sensitized solar cells is a dye sensitized solar cell using nano titanium oxide, i.e., anatase, which was developed by Michael Gratzel et al. of the Swiss Federal Institute of Technology, Lausanne (EPFL), Switzerland, in 1991.
The dye sensitized solar cell can be produced at a low cost, and since it uses a transparent electrode, there is an advantage in that it can be applied to external glass walls of a building or a glass greenhouse. However, the dye sensitized solar cell has a limitation in application for practical use due to low photoelectric efficiency.
The photoelectric efficiency of a solar cell is in proportion to the quantity of electrons produced from the absorption of solar beams. Thus, to increase the photoelectric efficiency, the quantity of electrons should be increased or the produced and excited electrons should be prevented from being used to cause electron-hole recombination. The quantity of produced electrons can be increased by raising the absorption of solar beams or the dye adsorption efficiency.
Particles of an oxide semiconductor should be prepared in a nano-size to increase the dye adsorption efficiency of each unit area, and the reflectivity of a platinum electrode should be increased or a micro-sized oxide semiconductor light scattering agent should be included to increase the absorption of solar beams. However, since the conventional methods have a limitation in increasing the photoelectric efficiency of solar cells, it is required to develop new technology that can improve the photoelectric efficiency.